New rules target water pumping in Palo Alto

Officials hope to encourage advanced construction techniques to reduce groundwater waste

Palo Alto residents have deep concerns about what's happening above the city's shallow aquifer -- namely, the millions of gallons of water that get pumped out of the ground every time someone in the area wants to build a basement.

On Wednesday night, a City Council committee waded into the complex issue of groundwater pumping by passing a slew of new requirements aimed at tightening the spigot and encouraging builders to adopt a less wasteful approach.

The new rules, which the council's Policy and Services Committee endorsed Wednesday night, build on the regulations that the council approved last year. They will also likely serve as a preamble to even more stringent regulations in 2018. Provided the full council adopts the committee's recommendations, starting in April contractors engaged in what's known as "dewatering" will have to demonstrate their ability to fill a truck in 10 minutes, limit pumping in residential areas to 10 weeks, offer to water trees and plants in neighboring properties, conduct pumping tests to gauge how much water is getting discharged and provide bi-weekly reports to the city.

In addition, the committee agreed to look at a more significant changes down the road, including ways to get people to adopt construction techniques that would significantly lessen the amount of water that needs to get pumped out.

The effort to beef up water-pumping regulations was inspired a grassroots movement that sprung up around the Old Palo Alto neighborhood, where most of the projects occur, and gradually spread to the wider community. While basement pumping is far from new, as several council members pointed out Wednesday, the issue has recently risen to the surface thanks to a combination of a statewide drought, the growing number of dewatering projects and the fact that most of them are in close to proximity to each other.

In 2015, there were 14 projects that required dewatering because they were located near Palo Alto's "shallow aquifer," according to Public Works staff. This year, there were eight, staff reported. Between them, these projects involved the pumping of about 140 million gallons of water, enough to supply all of the city's water needs for more than 17.5 days (Palo Alto currently uses about 8 million gallons per day).

Last year, the council responded to spreading community concern by adopting a slew of new rules, including a requirement that applicants supply a "statement of effects" of the groundwater pumping on nearby buildings and that they supply fill stations to recapture non-potable groundwater and allow it to be used for things like irrigation and construction cleanup.

While these rules will apply for the 2017 dewatering season, which runs from April 1 to Oct. 31, the city has more sweeping ambitions for 2018 and beyond. On Tuesday night, the council committee agreed that the most effective mitigation is incentivizing people to change the way they pump water.

The proposal was championed by local architect Dan Garber, who has spent the past year analyzing the dewatering problem together with Keith Bennett, founder of the citizens group Save Palo Alto's Groundwater. On Wednesday, residents wearing stickers with the group's name filled up (and spilled out of) the conference room during the committee's deliberation and about two dozen addressed the council. They urged a broad range of solutions, from a moratorium on groundwater pumping to a fee for each gallon of water discharged into the city's storm drains.

"We want effective regulations that minimize the waste of groundwater for all projects that commence in 2018 and beyond and we want improvements in the current process that make meaningful reduction in groundwater pumped in 2017 while obtaining accurate data to guide regulations in 2018 and onward," Bennett told the committee.

While some residents lamented the high number of basement projects, the committee agreed that the problem isn't really the basements, which Councilwoman Liz Kniss noted have been getting built for generations (her house, built in 1929, has one, she noted). She said she doesn't want to get basements to "get a bad name."

"It's about water," Kniss said. "Are we wasting water and how can we conserve it?"

Others agreed. Garber noted that most basement builders today use "broad-area dewatering strategies," which generally means building wells and then pumping the water out of the ground to enable excavation. Because of the nature of Palo Alto's soil, this often results in the surfacing of millions of gallons of water.

The alternative to this, he said, is a more localized approach which uses a cut-off wall to separate the basement area from the rest of the soil and only pumps out the water inside the cut-off wall. Garber recommended that the city consider two paths on developing dewatering regulations: one for builders who use the broad-area approach and the another for those willing to go the localized route. The idea, he said, is to provide incentives for builders to use the latter approach.

The council committee agreed wholeheartedly and voted 2-1 to make the near-term changes and to explore incentives for encouraging cut-off walls that would take effect in 2018. Even Councilman Tom DuBois, who voted against the motion, only did so because he felt it doesn't go far enough. In addition to all the things in the proposal, DuBois said the city should explore establishing a moratorium on basement pumping and imposing a fee for each gallon discharged. His two colleagues, Kniss and Vice Mayor Greg Scharff, both felt this would be going to far.

Among the changes that the committee recommended is a pump test. This was inspired by staff's recognition that the studies that contractors submitted to the city last year were by and large inaccurate. A new report from Public Works staff noted that they predicted "lower flow rates than occurred."

"The calculations were not well supported and were not readily verifiable," the report stated. "Evidence from community members suggests that the very low predicted groundwater drawdown levels may have been substantially exceeded."

Phil Bobel, assistant director of Public Works, said the pump test verifications will help address these inaccuracies. He also supported the idea of waiving the requirement for a study altogether for projects that rely on advanced construction techniques such as cut-off walls to minimize the water impact. While the city is unlikely to actually require localized solutions, it could create performance standards that would strongly incentivize builders to use such techniques.

"We're probably moving toward advanced construction techniques, but we don't have other cities that have done it, we haven't done it ourselves on residential properties," Bobel said. "We need to make sure that before we regulate, that this option is real and there aren't unintended consequences."


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29 people like this
Posted by Laurie Styles
a resident of South of Midtown
on Dec 15, 2016 at 2:59 am

Individual homeowner construction sites have pumped water out for years at a time. I've contacted the city years ago regarding this but to no avail. Pumping water out for years next to the superfund site has been so clever. Take action now not in 2018.

14 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Dec 15, 2016 at 10:14 am

Cate, who's 8 years old and in 3rd grade, showed a video that she made below to the Policy and Services Committee. It's simple, clear and accurate.
Watch it here:
Web Link

34 people like this
Posted by Phil Farrell
a resident of Palo Verde
on Dec 15, 2016 at 10:40 am

The most effective way to minimize wasting of groundwater from basement excavations is to discourage basement construction! Right now, basements are "free" - they don't count at all against the zoning floor area ratio lot coverage limits. This encourages maximum sized basements, which have other negative effects besides wasting groundwater. I've seen so many lots that have been cleared of mature trees because the excavation hole for the basement of the new home basically extends to the edges of the lot. These newcomers who want a maximal home are negatively affecting the rest of us by destroying tree canopies and wasting groundwater. "Charging" for the basements would reduced these negative effects. I suggest that 50% of the basement square footage be counted against the allowed floor area ratio lot coverage. That would discourage these giant basements, reducing the negative effects considerably.

26 people like this
Posted by Novelera
a resident of Midtown
on Dec 15, 2016 at 10:42 am

Novelera is a registered user.

I would love to see the plan implemented to somehow wall off the area of the proposed basement and only pumping that area's water. There have been four basements dug on my street. I have significant cracks along the rim of my walls where they meet the ceiling. I had to have my locks changed because the dead bolts didn't work any more. The house was sinking a bit, causing the bolt not to enter the hole correctly. The tree in my front yard has a main branch which kind of split where it joins the trunk. This caused a large amount of other smaller branches to land on my house. I have to trim constantly or the greenery hits me in the head in the driveway. I have lived in my house for 34 years and had no problems like this until the last year or maybe two.

24 people like this
Posted by ACR
a resident of Old Palo Alto
on Dec 15, 2016 at 11:25 am

Thanks to Tom DuBois for standing up for residents.
No thanks to developer/realestate supporters Kniss and Scharff who are concerned that putting any limits on outsized profits is "going too far."
Developers rule,

11 people like this
Posted by gardener
a resident of Leland Manor/Garland Drive
on Dec 15, 2016 at 11:27 am

Why are the spigots always locked?

We'd love to use some of this wasted water, but it seems the spigots lock combo/key is only provided to direct neighbors??

Anybody have info about this ?

Like this comment
Posted by moi
a resident of Another Palo Alto neighborhood
on Dec 15, 2016 at 1:29 pm

Too bad this journalist couldn't come up with any puns. The subject seems so ripe and all. . . .

7 people like this
Posted by Rick
a resident of Meadow Park
on Dec 15, 2016 at 2:00 pm

Umm, so this water just flows underground and right into the bay anyway....

17 people like this
Posted by Wassup with the Tax Assessor?
a resident of Evergreen Park
on Dec 15, 2016 at 2:24 pm

So why hasn't the office of the county tax assessor caught on to what is happening here?

Some of these basements have more square footage than the house above them-- three stories deep with bedrooms, bathrooms, kitchens, dining and living rooms!

New basements are potentially a large source of tax dollars, the taxation threat will discourage groundwater pumping, and basements built before 2005 can be grandfathered in!

San Jose had a decades-long problem with the whole city sinking. They banned the pumping of groundwater, and the sinking ceased, even improved!

15 people like this
Posted by Bea
a resident of Triple El
on Dec 15, 2016 at 3:20 pm

Sorry, but the "groundwater flows out to the bay anyway" argument doesn't work. Yes, it flows in that direction, but more to the point, it acts as a barrier to incursions of saline bay water, something that was happening in Palo Alto a couple of decades ago and had to be dealt with because of the pollution bay water introduces into our groundwater aquifers. Santa Clara Valley Water District has strong feelings about that issue - as they had to deal with it. When you remove ground water and allow even a temporary gap, bay water can come in (again) and we have that problem once more...

12 people like this
Posted by scared neighbor
a resident of Duveneck/St. Francis
on Dec 15, 2016 at 3:56 pm

There is a home being built very close to us with a basement placed in a huge hole in the ground, which had incredibly fast gushing de-watering until very recently. The audible flow of the water down this pipe to the storm drain was stunning.
I am scared about effects to us nearby neighbors with respect to settling, cracks and other detrimental effects of OUR houses (some have noted neighbor trees may be adversely affected.) At a MINIMUM, there ought to be a hefty charge for digging a basement in a flood zone and de-watering and pumping (that may be needed periodically thereafter?) When we moved here, we were told a basement was not permitted (!) yet the homeowner of this project is more in the flood zone than we are. I also think the square footage of the basement (if permitted) should be taxes by Santa Clara County Assessor.
Meanwhile, some at San Francisco's Millennium Tower are blaming nearby de-watering for their sinking and settling and tilting woes. Very worrisome.
Neighbors should count, too, in this city - not just the applicant (when tearing down and re-building in an entirely new way - added basement and de-watering).
Thank you for paying attention to this issue.

6 people like this
Posted by Steven
a resident of Evergreen Park
on Dec 15, 2016 at 4:29 pm


The city assessor does take into account the basement when calculating what the property taxes should be. The difference a basement gives is it allows the homeowner to exceed the livable square footage limit on the lot since the basement is below ground.

8 people like this
Posted by Save Palo Alto's Groundwater
a resident of Old Palo Alto
on Dec 15, 2016 at 7:04 pm

Thank you to all who wrote letters, showed up and spoke up for reducing groundwater waste for construction purposes at the Policy and Services Committee on Dec.14th. Thanks to your support and advocacy, together we changed the game!
It’s clear that the Policy and Services Committee and City Staff now understand that wasting water is the issue, and that it’s not acceptable politically. Or morally. Or for any city that thinks of itself as sustainable. They also know that alternative construction methods are available and practical.
See our blog Web Link for more.
One of the highlights of the many presentations to the Policy and Services Committee was the 2-minute animated video made by Cate A, an 8-year old in 3rd grade. The message is powerful – please share with your friends.
Web Link...

5 people like this
Posted by WaterConspiracies
a resident of Community Center
on Dec 15, 2016 at 8:38 pm

I have a well, and periodically measure the shallow groundwater.

Guess what - it's completely unaffected by the building projects in town. 14 houses dewatered, and the effect is so small to be unmeasurable.

its just not a problem.

2 people like this
Posted by Crescent Park Dad
a resident of Crescent Park
on Dec 16, 2016 at 12:38 am

Steven is correct. Building a basement counts as part of the "improvement" costs that are associated with development fees and county property taxes. Basements are excluded from square footage calculations and should stay that way. That would be consistent with just about every city/county in the US.

3 people like this
Posted by Save Palo Altos Groundwater
a resident of Old Palo Alto
on Dec 16, 2016 at 5:44 am

We'd love to have your well data.
Could you kindly send us an e-mail to letting us know how we could get the data to add to our well database.


3 people like this
Posted by ChrisC
a resident of Community Center
on Dec 16, 2016 at 6:59 pm

The reason the taps are locked is because the city requires them to be. Apparently they are worried about pranksters using them to flood the streets for fun, and so someone from the city needs to unlock them to fill up a truck.

3 people like this
Posted by Ed
a resident of Downtown North
on Dec 19, 2016 at 10:20 am

Make any basement space count towards the square footage of the home, and therefore, contribute to property tax assessment of the home. I believe basements are 'free' as far as tax purposes go, and yet, are part of the living space of any house with one. Close this ridiculous loop-hole, and demand for basements should plummet.

Simply 'encouraging builders to adopt a less wasteful approach' with respect to wasteful water pumping, as suggested in the article is laughable. Without firm rules with financial penalties, Any such 'suggestions' put forth by the city will be ignored. How about property owners wanting to add a basement be required to post a bond valid for some number of years so that when slabs or foundations are wrecked next door, or once thriving trees die, the responsible party pays up. Bonds would need to be in effect for several years as the damaging affects of disrupting the water table take time to manifest themselves.

Palo Alto city planners can, and should do more to protect each home owners, not just those with the money to build basements and literally disrupt and damage their neighbors property in the name of personal property rights. What about the rights of those affected?

In previous reports, Phil Bobel, assistant director of Public Works, has previously demonstrated a profound ignorance of the issue and I am unaware that he has any geologic or hydrologic background from which to make any informed opinion or decision. That he is still involved in these discussions I fear reflects a very poorly informed decision making process. The city really needs to hire an expert in the field if they hope to make a science based policy on this important issue.

1 person likes this
Posted by Crescent Park Dad
a resident of Crescent Park
on Dec 19, 2016 at 11:06 am

Basements already count towards the valuation of your property taxes. Property taxes are assessed through two components: the value of the land and the value of all improvements on the property. Construction and/or existence of a basement is included as part of the calculation for the "improvements" on the property.

3 people like this
Posted by Foundation Engineer
a resident of Charleston Meadows
on Dec 19, 2016 at 4:45 pm

The enacted regulations have NO scientific basis.

Its more tin foil hat thinking from a town that should know better.

Its all about what LOOKS good and what FEELS good...not about what is actually happening.

Trees get their water in the top three to four feet of soil. That's it! Trees do not have tap roots. They DON'T!

While it looks like water is being horribly wasted...its not. The ground water is flowing to creeks and the bay underground. De-watering removes only a VERY small volume of water directly under the foundation. The water gets put directly into the creeks or bay. That's probably should not even use this water because its the MOST likely to have solvent/pesticide/fertiliser contamination.

[Portion removed.]

Like this comment
Posted by Me 2
a resident of Old Palo Alto
on Dec 20, 2016 at 7:17 am

"Again, the Council has bent to the noisy lunatic fringe rather than leaning on quality science. These are the times we live in."

Haha. And this in the center of a state that accuses the other side of not believing in "science." It seems for some science is not a process but a religion.

3 people like this
Posted by Please...
a resident of Another Palo Alto neighborhood
on Dec 20, 2016 at 9:11 am

@Foundation Engineer. For your information,
if a tree does not have a tap root then it has a
a horizontal root system. The roots of a redwood tree or oak tree, both protected trees under
City ordinance, may extend out 75-100 feet. The redwood roots are 5-6 feet deep, not 3-4 and can
do down 10 feet. Dewatering can cause subsidence to adjacent properties during the dewatering if not long-term as well. Subsidence requires recharging of ground water with imported water
which can become an issue in drought conditions. All of the redwood trees at Palo Alto Sq are dying. Do you have any knowledge as to why that is happening? The redwood trees in the forest at Riconada Park are in trouble, outside the main library as well.

1 person likes this
Posted by Better Dewatering methods
a resident of Community Center
on Dec 20, 2016 at 2:18 pm

Just by reducing the depth of the pumps to a few feet below the basement you can reduce the majority of water pumped. How come this wasn't mandated?

2 people like this
Posted by Foundation Engineer
a resident of Charleston Meadows
on Dec 20, 2016 at 3:16 pm

@ Please. Thank you for confirming my point.

Tree roots DO NOT grow into ground water (unless you are a cypress). The trees roots grow in a mat around the tree to a very shallow depth. They do this to provide structural support for the vertical trunk/branch mass. The advantage of growing in a mat around the tree is that it provides a larger surface area to collect the water from above.

From my understanding of redwoods at Palo Alto Square, it is very important that the mat around the tree receive moisture from above. In the forest, there is a mat of dead leaf matter that helps retain moisture in the soil above the tree root system. The dew that drips off the tree needles drops to the leaf debris and keeps the soil moist for the redwoods. When you plant a redwood in the middle of a parking lot, (and cover the tops of the roots with black pavement, you deny the tree roots moisture from above that the tree needs. Dry hot roots do not make for happy trees. Then again...I am not a tree consultant...just a humble foundation engineer. I'm sure there is a bit more to this...but I think I've hit the important point.

Subsidence is an issue when you remove water from under very specific soil types. But more related to depressurising an aquifer...which would be much deeper than the three or four feet of de-watering require for a typical residential foundation.

Posted by Name hidden
a resident of Midtown

on Jul 24, 2017 at 5:05 pm

Due to repeated violations of our Terms of Use, comments from this poster are automatically removed. Why?

Sorry, but further commenting on this topic has been closed.

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